Wikibooks: Structural Biochemistry/Enzyme/Specificity
=Introduction= A key feature of nearly all enzymes is that they bind their substrates with a high affinity or high degree of specificity. For example because hexokinase binds glucose very well we say it has a high affinity for glucose. On the other hand hexokinase has a low affinity for other sugars...
| Format: | Book |
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| Language: | English |
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| Online Access: | https://en.wikibooks.org/wiki/Structural_Biochemistry/Enzyme/Specificity |
| Summary: | =Introduction= A key feature of nearly all enzymes is that they bind their substrates with a high affinity or high degree of specificity. For example because hexokinase binds glucose very well we say it has a high affinity for glucose. On the other hand hexokinase has a low affinity for other sugars such as fructose and galactose which have similar structures to glucose. The interactions between enzymes and their substrates have been studied by a German scientist Emil Fischer who proposed that the recognition of a substrate by an enzyme resembles the interaction between a lock and key only the right sized key (the substrate) will fit into the keyhole (active site) of the lock (the enzyme). Further studies revealed that the interaction between an enzyme and its substrates also involves movements or conformational in the enzyme itself. These conformational changes cause the substrates to bind more tightly to the enzyme a phenomenon called induced fit. The enzyme catalyzes the conversion of reactants to products only after this conformational change takes place. =Enzyme= Enzymes are used to accelerate reactions. Most enzymes provide accelerated reaction mechanisms by reducing the energy required to obtain the transition state between reactants and products. For example carbonic anhydrase one of the fastest enzymes known is capable of transforming carbon dioxide into carbonic acid at a rate of 1 million molecules per second 1 . The reactants used in a reaction are also known as substrates. These substrates require enzymes to be specific so that enzymes act on the correct substrate or bond to catalyze the desired reaction. More precisely the specificity of an enzyme is due to the precise interaction of the substrate with the enzyme. This precision is a result of the intricate three dimensional structure of the enzyme protein 2 . =Enzyme ligand complex= Enzyme specificity results from the binding site features. In other words the specificity of an enzyme and substrate could be analogous to a lock and a key. The key ... |
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